The invention relates to a network management system for configurating and reading data and states of several network elements, such as telephone exchanges, of a telecommunication network by giving the network elements commands according to their internal command language when at least some of the network elements of the telecommunication network have mutually different internal command languages, the system comprising memory means for storing parameters describing the command language of each network element, means for generating service requests in a network element independent format, conversion means for converting the network element independent service requests into commands according to the command language of the network element which is the target of service by means of parameters describing the command language of the network element, means for sending the generated commands to the network element which is the target of service, means for receiving command responses sent by the network element which is the target of service and for converting them into a network element independent format.
Modern telecommunication networks comprise a large number of different kinds of network elements, such as telephone exchanges, transmission systems, etc., the states and data of which the network operator must read and change daily. Typical examples of recurrent changes are deletion, addition or modification of subscribers, and different changes in routing for instance when a network element is overloaded. The exchanges are controlled either by remote control or locally by in-putting commands for configurating their data, changing their states, etc. A modern telephone exchange may have several hundreds of different commands by which exchange specific data can be modified. On the other hand, many kinds of data are received from the exchanges: alarm outputs, measurement reports, charging data.
There have been attempts to develop network management systems which in a centralized manner would carry out the configuration and reading of data and states of different network elements in a telecommunication network. At present, the standardization organizations (e.g. ETSI, CCITT) are specifying the management standards for telephone exchanges and all network elements in general. Such a concept is called a TMN (Telecommunication Management Network). Standardized interfaces between the control system and the network elements are of crucial importance in standardization. However, such new standardized solutions will not be available for a long time and will require planning with respect to all network elements, wherefore it takes a long time before they are used for controlling all the network elements. Until then, the network management systems to be implemented must communicate with existing network elements in a manner which they understand in their internal command languages, which in telephone exchanges, for example, are manufacturer and type specific. New versions of command languages are created with new system generations of different telephone exchanges of the same manufacturer and with new software versions. This poses great problems for outside network management systems which are completely independent of the network elements but which should, however, master the different command languages and their versions. Network management should further be capable of adapting to a new command language whenever a new network element is introduced to the telecommunication network. At its worst, this results in that the operator of the network management system must continually modify his network management software in order to meet this requirement. The network management becomes more and more difficult when the number of network elements increases.
U.S. Pat. No. 4,782,506 discloses a network management system which operates one or more exchanges connected thereto. The management system is provided with correlation memories, in which there are stored the structural data of both commands and command responses of different exchanges. In addition, the formal representations of different operations are stored in SDL/PR format in the correlation memories; in fact, these representations describe the management operations in detail, i.e. how the different operations of the exchange are performed step by step, command by command. These data have contributed to network management that is to a great extent independent of the type of the system to be controlled. The operator gives commands in a universally applicable formal format, from which they are converted into the command language of the exchange. The structural representations of the commands and command responses of all exchanges are written and updated manually through a specific editing console in relational memories.
In practice, however, network management systems manage very large telecommunication networks, which may comprise dozens, even hundreds of exchanges. The exchanges are continuously modified, and new exchanges are connected under the management. Software is updated, and often the changes can also be seen in the interface with the management system. The syntax of commands may change: new parameters are added, new fields appear in the command responses, or completely new commands may be generated. In order for the management system to function appropriately, it is crucial at the same time to keep the correlation memories up to date. Even small modifications of command responses, in particular, may lead to total malfunctions. It is nevertheless problematic to keep the correlation memories up to date. It is very laborious to perform this task for instance by manual programming, and errors are easily made, as, e.g., modern telephone exchanges may include hundreds of different commands.